init: use the correct path of the templates directory again
In
df93e407f06 (init: refactor the template directory discovery into its
own function, 2024-03-29), I refactored the way the templates directory
is discovered.
The refactoring was faithful, but missed a reference in the `Makefile`
where the `DEFAULT_GIT_TEMPLATE_DIR` constant is defined. As a
consequence, Git v2.45.1 and friends will always use the hard-coded path
`/usr/share/git-core/templates`.
Let's fix that by defining the `DEFAULT_GIT_TEMPLATE_DIR` when building
`setup.o`, where that constant is actually used.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>